Due to the increased popularity of the game of golf as a recreational and professional sport over the past several years, a need has arisen for a golf putting club that provides golfers of all skill levels with the opportunity to maximize putting performance. As a result, golf club manufacturers have begun introducing putters that are designed to minimize the adverse effects of errors in putting technique. One aspect of this effort has been to introduce a putter with modifications designed to create topspin on the golf ball as it is struck by the putter head. Because of the frictional forces created by the roll of the ball on the ground, the optimal putt is one in which the ball is provided with consistent overspin for accuracy and speed.
Most conventional putters have a flat face with a positive loft that contacts the golf ball at the tangent point below the center of the ball. The average golf ball is 1.66 inches in diameter, thus placing the centerline 0.83 inches from the ground, (not considering the height of the grass, etc.). Although the height of the putter face is usually larger than 0.83 inches, the ball must nevertheless always be contacted at the above-described tangent point which intersects the centerline of the ball, since the non-angled putter face or positive angled lies in a plane perpendicular to the ground or below the centerline of the ball. Because this contact point lies on and not above the centerline of the ball, overspin will not always be created when the club face strikes the ball, and as a result the ball will sometimes "skid", "bump", or sometimes even become airborne, depending on the length of the putt, length and direction of the grain of the grass.
Considering all the variables beyond the golfer's control which can affect the line and speed a putt, and considering the change in these variables which results from the differing conditions encountered at each different green on each different day, it is evident that a need exists for a putter which can minimize the adverse effects of some of these variables regardless of the conditions encountered. Providing a putter which imparts consistent overspin to the ball will accomplish this by eliminating the tendency for the ball to skid, bump or become airborne. The present invention solves this problem by providing a negatively angled loft on the face of the putter, as contrasted with the non-angled club face of most conventional putters the positively angled club face loft of most conventional golf irons. This negative loft allows the putter face to contact the ball above the centerline with each stroke, imparting topspin on the ball 100% of the time, independent of most variable putting conditions.
One putter that makes the claim of producing topspin is the "Masteroll" Putter found in the September 1995 issue of the Competitive Edge Golf Magazine (at page 10). This putter is round with a larger diameter than the ball, and does create overspin, but the effectiveness of the putter is dependent on some conditions being ideal. For example, if the length of grass varies, so does the quality of overspin produced by this putter, due to a variation in the point on the club face at which the club contacts the ball. Because the putter has a rounded vertical cross-section along the club face, this variation in the contact point will not eliminate the tendency of the ball to "climb" to overcome the friction opposing its roll. Although its overall performance is better than in many conventional designs, because of this putter's rounded club face a consistent repeatable overspin will not be provided to the putt, resulting in some degree of bumping and skidding in the putt.
Another putter that makes the claim of producing topspin is a putter that creates "rounder rolls", as again shown in the September 1995 issue of the Competitive Edge Golf Magazine (at page 19). This putter is claimed to always strike the ball above the ball's center of gravity. However, due to the fact that most conventional golf balls have a lighter half and a heavier half, this will not always be the case, depending on which half of the ball is oriented nearer to the ground when struck by the club face. (See September 1995 issue of Competitive Edge Golf Magazine, at page 22). Thus, ideal conditions must also exist (or an inertial mass-balanced golf ball must be used) for topspin to be consistently produced with this putter.
There are a number of negative loft putters disclosed in the prior art, including U.S. Pat. Nos. 5,344,149; 5,407,196; 4,664,385; 1,467,714; 4,795,158; D204,279; 5,348,301; 3,333,854 and 4,881,739. However, all of these putters have a planar face, which results in an exaggerated off-center trajectory for the ball, if the angle of contact of the putter face is adjusted to cause the ball to travel a non-straight line path to the hole to account for a sloping green. With a conventional planar putter face, the golf ball will travel a path which is approximately 1.71 (or 15/7) times more angularly skewed than the putter face angle of contact. In other words, if the angle of contact with conventional planar putter face is intentionally or accidentally misaligned by 1 degree from that which would produce a straight line trajectory to the hole, the ball will travel a path that is approximately 1.71 degrees to the right or left of the hole. The present invention minimizes this trajectory error by providing a putting face which is convex on an arc of radius 5 to 84 inches. This convexity will produce a ball trajectory which is at most equal to the putter face contact angle misalignment, and in most cases will in fact reduce this misalignment to be less than that created by the putter face. In other words, if the angle of contact with putter face of the present invention is misaligned by 1 degree from that which would produce a straight line trajectory to the hole, the ball will travel a path that is less than or equal to 1 degree to the right or left of the hole, thus producing a more accurate alignment with the hole.
A putter with an angled face is disclosed in U.S. Pat. No. 5,382,019. However, the radius of curvature for this club face lies in the same plane as the axis and centerline of the ball, and therefore will not provide the claimed topspin feature 100% of the time, since the ball must be struck on the upswing to produce the overspin effect. Additionally, the shape of the putter face disclosed in U.S. Pat. No. 5,382,019 makes it difficult for the golfer to line himself up at right angles to the hole, since from the golfer's view, the putter face provides no visual indicator with which to gauge hole-to-ball alignment. Thus, unless the ball is struck at the exact geometric center of the putter face, a tangential trajectory similar to that described above will result, causing an unintended deviation in the path of travel of the ball to the hole.
Thus, it is an object of the present invention to provide a golf putting club having a negatively lofted putting surface for providing top spin to a golf ball.
It is a further object of the present invention to provide a golf putting club having a convex putting surface for minimizing the amount of angular displacement of a golf ball that is struck on an angle to the central axis of the putter face.
It is a further object of the present invention to provide a golf putting club which contacts the golf ball above the centerline to impart topspin on every putting stroke, independent of variable putting conditions.
It is a further object of the present invention to provide a golf putting club having a convex club face for producing a ball trajectory which is at most equal to the contact angle deviation created by misalignment of the putter face, and which will ideally reduce the amount of angular misalignment created by the putter face.